package lightdm 1.10.1-0ubuntu1 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1

[tguha]

I want to get rid off xubuntu and xfce but getting failed and came up with these bugs.

ProblemType: Package
DistroRelease: Ubuntu 14.04
Package: lightdm 1.10.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-39.66-generic 3.13.11.8
Uname: Linux 3.13.0-39-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.14.1-0ubuntu3.5
AptOrdering:
 xubuntu-desktop: Purge
 ubuntu-desktop: Purge
 lightdm: Purge
Architecture: amd64
Date: Fri Nov 14 20:08:33 2014
DuplicateSignature: package:lightdm:1.10.1-0ubuntu1:subprocess installed post-removal script returned error exit status 1
ErrorMessage: subprocess installed post-removal script returned error exit status 1
InstallationDate: Installed on 2014-11-11 (3 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
LightdmConfig:
 [SeatDefaults]
 autologin-user=
SourcePackage: lightdm
Title: package lightdm 1.10.1-0ubuntu1 failed to install/upgrade: subprocess installed post-removal script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)